There's only one thing standing between you and a makeup meltdown: a makeup primer. A serious contender for MVP of your makeup bag, primer comes in many forms. Face primers keep your foundation from getting splotchy and oily, eye primers prevent your perfectly applied smoky eye from creasing and lip primer keeps your bold lip in place all day. But finding the best primer can be a daunting task -- which is why we have a huge database of makeup primers reviewed by our readers. Go ahead, give us your opinion on the best and worst primers.